android 笔记 ----- 按钮Button应用

让按钮有按下效果

这个其实很简单，首先，准备两张按钮的图片，分别是正常状态和按下状态，我就举 btn_normal.png btn_press.png 为例子，通过下面的XML就实现了不同状态下按钮的效果。调用时，只要在 android:background=”@drawable/btn” 就好了，其中btn就是下面的btn.xml 文件，放在drawable文件夹下面。

<?xml version="1.0" encoding="utf-8" ?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
	<item
		android:state_pressed="false"
		android:drawable="@drawable/btn_normal" />
	<item
		android:state_pressed="true"
		android:drawable="@drawable/btn_press" />
	<item
		android:drawable="@drawable/btn_normal" />
</selector>

自定义button的实现:未选中/按下/选中效果

package com.test.TestButton;
 
import android.app.Activity;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.StateListDrawable;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
 
public class TestButton extends Activity {
   @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Integer[] mButtonState = { R.drawable.defaultbutton,
                R.drawable.focusedpressed, R.drawable.pressed };
        Button mButton = (Button) findViewById(R.id.button);
        MyButton myButton = new MyButton(this);
        mButton.setBackgroundDrawable(myButton.setbg(mButtonState));
    }
 
    class MyButton extends View {
 
        public MyButton(Context context) {
            super(context);
        }
        //以下这个方法也可以把你的图片数组传过来，以StateListDrawable来设置图片状态，来表现button的各中状态。未选中，按下，选中效果。
        public StateListDrawable setbg(Integer[] mImageIds) {
            StateListDrawable bg = new StateListDrawable();
            Drawable normal = this.getResources().getDrawable(mImageIds[0]);
            Drawable selected = this.getResources().getDrawable(mImageIds[1]);
            Drawable pressed = this.getResources().getDrawable(mImageIds[2]);
            bg.addState(View.PRESSED_ENABLED_STATE_SET, pressed);
            bg.addState(View.ENABLED_FOCUSED_STATE_SET, selected);
            bg.addState(View.ENABLED_STATE_SET, normal);
            bg.addState(View.FOCUSED_STATE_SET, selected);
            bg.addState(View.EMPTY_STATE_SET, normal);
            return bg;
        }
    }
 
}